Pipe threading machine



Jan. 12, 1937. w. 1. BENNINGHOFF PIPE THREADING MACHINE 3 Sheets-Sheet 1 Filed Jan. 28. 1935 MC 9r Arr-onus)"- 1937- w. L BENNINGHOFF 2,067,626

PiPE THREADING mcnnm Filed Jan. 28, 1955 3 Sheets-Shoat 3 55 Patented Jan; 12, i937 UNITED; STATES,

PATENT OFFiCE PIPE 'rnnnnnme MACHINE. William L. Benninghofl, Shaker Heights, Ohio Application January 28, 1935, Serial No. 3,121

3 Claims.

The invention relates to mechanism for forming threads on pipes or other similar bodies.

An important object of the invention is the provision of a machine well adapted to cut accurately-forined screw threads on pipes and particularly on pipe sections of relatively large diameter and considerable length.

A further object'of the invention, also ancillary to.the object first stated, is the provision in a machine of the character stated of-means for supporting the pipe while being threaded which is adapted to hold the pipe fixedly and accurately in position without distortion of the portion of the pipe bein'g threaded.

Another object of the invention is the provision of a pipe-threading machine such as last referred to adapted to handle relatively large and long pipe sections and to beloaded with the work and unloaded rapidly and easily.

Further objects of the invention, more or less ancillary or incidental to those" already stated, will be apparent from the following description of the preferred form of embodiment shown in the accompanying drawings.

In the drawings,

Fig. 1 is a side elevation of a machine embody ing the invention with some of the parts broken away to better disclose details of construction and with the thread-cutting tool proper in retracted position. as shown by full lines and in advanced position as shown by dot-and-dash lines. a Fig. 2 is a plan view of the machine.

Fig. 3 is anenlarged; fragmentary section show,- ing a portion of the thread-cutting tool and one of the pipe clamping mechanisms of the machine.

Fig. 4 is an enlarged side elevation of the pipe clamping mechanism shown in Fig. 3.

Fig. 5 is a vertical section on the line 55 of Fig. 3 and Fig. 4.

Fig. 6 is a horizontal section on the line 6-6 of Fig.5.

Fig. 7 is a vertical sectional view showing a second form of the interchangeable face blocks for the clamping jaws.

the usual practice in the threading operation either to rotate the pipe while the thread-forming tool is fed axially in relation to the pipe or to hold the pipe against rotation but feed it axially toward a rotating thread-forming tool.

. With such prior machines it has been found to, be practically impossible to form uniformly accurate screw threads on pipes, particularly where pipe sections of relatively large diameter and of considerable length are to be threaded. This 'which is mounted ina gear box I2 bolted to the In prior pipe-threading machines it has'been unsatisfactory result in the case of prior machines is due, I believe, either to the fact that the pipe while being threaded is not maintained in a true-axial relation to the thread-cutting tool or to the fact that that part of the pipe being 5 threaded is distorted, or is due to both of these facts. In carryingout my present invention I have sought to overcome these difliculties by providing means adapted to hold the pipe accurately in fixed position and without distortion of the threaded parts while the screw thread is being formed. r H

Referring indetail to the construction illustrated, the machine is provided with a bed-frame designated in its entirety by the numeral I and comprising a. section 2 upon which the threadcutting tool and the driving mechanism therefor are mounted and a section 3 upon which the pipe-supporting means are mounted, the *two sections 2 and 3 being preferably rigidly secured together as by bolts. 4, 4. The frame section 2 is provided with'ways 2a, 20 upon whichis slidably mounted a carriage 5. In one end of this carriage is rotatably mounted a threadingv die designated as an entirety by 6, said threading die having a body 1 formed with a trunnion part Ia which. is rotatably mounted in bearings in the carriage 5, one of said bearings being shown at 8. A motor 9 mounted on the top oi. the carriage 5 serves to rotate the die 6 through the medium of a suitable train of gears, not shown,

within the gear box I0 and the frame or casing of the carriage. The train of gears referred to has a suitable spline connection with a shaft II end of the frame section 2. The shaft ll through a train of gears I3 enclosed in the gear .box I2 rotates a feed screw I4 which operatively' engages a nut I5 fixedly secured to the carriage 5 so that the rotation of the feed screw I4 is 40 adapted to feed the carriage 5 forward (to the right in Fig. 1) or to retract it, according to the direction of rotation of the screw. Consequently the motor 9 is adapted to rotate the threading tool 6 and simultaneously feed said tool axially forward to the work. v

To effect a rapid retraction of the carriage 5 I provide a separate motor I 6 which is connected by suitable gears with the train of gears l3 in a manner to rotate the feed screw I 4 at a higher speed than is feasible with the gear connection between the motor 9 and said feed screw. The hand lever I! (a part of which is broken away in Fig. 1) is connected by suitable link and lever devi es designated as an entirety by II! with a clutch 66 of gears between the motor 9 and said feedscrew or vice versa.

The detailed forms of construction of the mechanism for rotating and axially feeding the threadv forming tool fi can be varied widely in/carrying out my invention and I have, therefore, deemed 10.

parts of the mechanism in full detail.

Similarly, in carrying out my invention the thread-forming tool itself may take a wide variety of known forms of such tools and it is unnecessary, therefore, to describe it in detail. As illustrated the tool 6 is of the same character as the threading die disclosed in my copendingapplicationSerial No. 743,801.;filed September 13, 1934, -;,fto;,,whioh reference may be had for a complete detail disclosureh For .the purpose of disclosing :the present invention it will suffice to state that the tool comprises a series of cutters or chasers l5 5 Fig 3 i, i,1dably, mounted on the front end of the ody '"tzsowas to be gradually retracted outb rdrinirelation to the pipe during the cutting operationrgin order to form the usual taper thread. 0 efiect such retraction of the-chasers they are peratively connected by cam devices with a structure 2| slidably mounted on the outside of the tubular tool body 1 and this slide 2 l. is in turn conneotedby-suitable. cam devices (not shown) with a-structure 22 slidably mounted inside the tool body 'i.= The inner slide 22 carries an adjustable plate22a adaptedto engage the end of the 5 pipe to be threaded so that when the tool. body l mis fed axially forward in relation to'the pipe the inner slide'22 is moved longitudinally of the'too'l body and, by its cam connection with the outer slide Zhefiects a similar longitudinal movement 40 of the latter on the tool body and in relation .to

' Ition preparatory tostarting another thread-cutting-operation. The chasers' I9 are mounted at 'ftlie extreme end of the cutting toolvin such a manner that they canapproach close to a work support; Slidably mounted on theelongated main frame section 3 are two pipe cla mp mechanisms desig- 60 .nated in their entireties by 23.and 25, respectively. These two clamping mechanisms are substantially the'same'in construction so thata description of the mechanism 23, as illustrated in the several 2 figures of the drawings, Will be understood as applyi gialso to the mechanism 24.. In Figs. 1 and 2 e e erence numerals applied to themechanism i ge are alsoiapplied to the corresponding parts of -the mechanism. 2 i insofar as those partsare 3Q gf thfilm ailil frame. The frame carries a rotatably mounted pinion 26 which mesheswith a rack 2'! attached to the under side of one of the ways (Figs. 4 and 5). By turning the pinit unnecessary to illustrate and describe such v other.

v -25 (Figs. 5 and 6).

The clam mechanismhas a rigid frame struc-- 25 formed to engage and slide upon the ways ion 26 by hand the .clamp mechanism 23 can be adjusted longitudinally of the frame 3.

3 The frame 25 is formed with two upward extending arms 25a, 255 which are spaced apart to form a relatively wide intervening space 28 (Fig. 5). Slidably mounted for horizontal movement in the arms 25a, 25?) are two pipe-gripping jaws 29, 30, each of which is' provided with a removable face or gripping block 3! secured to the jaw by bolts 32, 32; The block 3| is preferably provided with hardened steel inserts 33 adapted to bite into the pipe held-by the jaws. To adapt the machine to handle pipes of different sizes the face blocks 3i are made removable and interchangeable so that by the use of blocks 3!, such as are I provide mechanism for actuating the jaws 25, v

30 which is adapted simultaneously to move the jaws alternatively toward or away fromeach other in a manner to maintain them in symmetrical relation to the axis of the thread-forming tool 6. This mechanism comprises two upright levers 3 3, 34 which are pivotally mounted on short shaft sections 35, 35. These shaft sections are adjustably mounted on a supporting shaft 55 which is rotatably mounted in bearings 31 and 38 in the frame 25, being heldagainst endwise movement by a thrust hearing at 39. The shaft sections 35 are formed with threaded transverse apertures to engage the sections 36a, 36b of the shaft 35, said sections being threaded oppositely to each other. The front end of the shaft 36 is fitted with a hand wheel 50 by which the shaft can be turned to adjust thepivots 35, 35 toward or away from each nected by links 5!, l! with their respective jaws 29 and 30. i i

To actuate the lovers 35, 35 I provide a pair of togglelinksflZ, 43 which are pivotally connected together: by a pin 54 carried by a cross head 55 slidably mounted in Ways 56 and 57 in the frame The other ends of the toggle links 52, 43 sli-dably engage raised pads-(i8, 38 formed on the frame 25 and are pivotally connected by links 19 49 to the lower endsof the levers-34.

Power means for actuating the toggle links comprises a reciprocating hydraulic motor 50- having a p'iston5l and a piston rod 52 which is connected to the cross head (Fig. 3). The piston of motor is actuated by a pump 53 which may conveniently be of the gear type and whichcanbe driven in either direction by an electric motor 54. The pump and its motor are supported upon an extension 250 of the frame 25. The

pump 53 and the motor 50 are connected by con -duits 55 and 58 and by driving the pump in one direction the motor piston 5| is moved in a. direction to straighten the toggle linkage and move the clamping jaws 29, '30 toward each other, while The upper ends of the levers 343 are conby driving the pump 53 in the opposite direction 1 the jaws 29 and 30 are moved away from each jothr.

The conduit '55 leading from one pressure chamber of the pump 53 and to the rear side of the motor piston 5| is provided with a branch conduit 51 leading to the supply reservoir of the pump; The conduit 51 is controlled by 'a spring-pressed check valve 58 which opens when the pressure in 1 conduit 55 rises to a predetermined value to permit escape of liquid through the branch conduit ,means 58a. by which the tension of the. valve spring can be adjusted to vary the pressure at which the valve opens. The detail construction 51. The relief valve 58 is provided with manual be li'mited to any desired value by suitable'ad- Lustment of means 58a. fit is apparent that-the jaw-actuating devices of. the clamp mechanism are adapted to move .the

jaws 29 and 38 simultaneously and equally toward orfrom each other according to the direc-" tionof movement of the hydraulic motor 58, thus serving automatically to center the pipe in relation to thetooli. By turning the hand wheel 86 to change the positions of the supporting shafts ofthe levers 34 the jaws can be adjusted toward and away from each other andthus adapt the clamp to hold pipes of a wide range of sizes.

As has been said, the,clamp mechanism 24 is similar to the mechanism 23, but it will be apparent that the relief valve, 58 of the mechanism 24 can be set difierently than the corresponding relief valveof the mechanism 23 so that thegripping pressures of the two clamps can at will be made ,diil'erent, v

The operation of the machine in the threading a of pipes will readily, be apparent from the foregoing description. .The clamps 2 3 and 24 are first adjusted tosuitable positions upon the bed frame 3 according to the size of the pipe sections to be threaded. In the drawings, for purposes of illustration, I have shown at W a pipe section of relatively large size and considerable length".

.With the clamps 23, 24 suitably positioned and with their clamping jaws retracted the pipe sectionW to'be threadedis readily placed in position by lowering it between the arms 25a, 25b andthe clamping jaws, no endwise movement of the heavy pipe section being necessary. With the pipe section lowered into position between the clamping jaws the latter are moved into operative engagement with the pipe by starting the pumps 53 of the two clamps in a direction to bring the clamping jaws together, and the'continued operation of the pumps cause the clamps firmly to hold the pipe section in alignment with the tool 6. By suitably adjusting the relief valves 58 of the twdr clamping mechanisms the maximum clamping 3 pressure for the clamp 23 can be made suihciently 60' rear end of the pipe section iirmly in fixed-aligrn- 'ment with theaxis of the threading tool but also great to hold the front end of the pipe firmly infixed position yet not great enough to cause any deformation of the cross sectional form of thepipe. On the other hand, the reliefvalve 58 of the clamp 24 can be set so that the latter clamp will exert a higher pressure not only to hold the to grip the pipe section strongly enough to obviate any turning of the pipe in theclamps. A

clamping pressure strong" enough forthis purpose may cause temporary deformation of the cross sectional form of therear section of the pide but as this deformation is atia point remote from the 7" section of the pipe to be threaded, it does not affect the form of the threads out.

With. the pipe section clamped in position as shown infFigs. 1 and 2 and with the threading tool 8 in retracted position as shown in full lines in said figures the motor 9 is started to rotate the threading tool 6- and simultaneously feed it forward to the work? Alternatively the higher speed feed driven by the motor It can be employed initially to feed the tool 6 forward until it is'close to the work and then the motor [6 can be thrown out and the motor 9 started. The operation of the tool 6 in cutting the thread need not be described in detail as it constitutes no part of the present invention. Suffice it to say thatwhen the tool has reached the end of the thread-cutting operation the tool, as indicated by dot-and: dash lines in Fig. 1, if it be of the type illustrated,

will automatically retract the chasers, whereupon the motor 9 is thrown out of operation and the motor it started to retract the tool and permit the pipe to be released from the clamps and removed preparatoryto theinsertion of another pipe'section or to the reversal of the pipe section for the threading of its other end. To release the pipe from the clamps, the pipe is supported while the pumps 53 are reversed and the clamping jaws separated until the pipe can be lifted from'between the jaws.

-It will be seen that by mounting the threading tool for both rotation and axial feed to the work I am enabled to support the work firmly in fixed position and thus maintain a highly accurate alignment of the work and the die, which is a condition essential to the formation of accurate threaded and limiting its clamping pressure so as c not to press the pipe out of round yet holding it firmly against later movement, the heavier pressure necessary to prevent rotation or endwise movement of the pipe being provided by a second clamp disposed suificiently remote fromthat part of the pipe being threaded so that temporary distortion of the cross sectional form of the pipecby the last named clamp does not-affect the form oi. the threaded partof the pipe.

The constructionbf the tool that the jaws of the clamp can be positioned close to the part of the pipe to be threaded insures a firm holding of the pipe without lateral distortion.

Obviously the positioning of the pipe in alignment with the tool proper is facilitated by the self-centering action of the pipe clamps; Also, the

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. construction of the clamps permitting pipes to be threaded to be directly lowered between j the clamping jaws contributes notably to the ease with which the machine can be loaded with the work and again unloaded.

From what has been said it will be apparent that the construction of the machine shown and described can be varied widely in various respects without departing from the in the appended claims.

What I claim is:

1. In a pipe-threading machine in which a thread-cutting tool movably mounted on-the machine frame is simultaneously rotated and advanced toward the work, the combination withthe machineframe of means thereon for iixedly supporting a section of 'pipe, in axial alignment with the tool while the latter operatively engages 6 and clamp 23 so invention as defined it, said means comprising a clamp adapted, without substantial distortion of the cross-sectional form of the pipe, to grip the said pipe sufliciently close to the part thereof to be threaded to hold said partof the pipe against movement transversely of its axis, and a second clamp adapted during thethreading. operation more strongly to grip the pipe at points sufiicient ly remote from the-part to be threaded so that local distortion of the cross sectional form of the pipe by said clamp will not affect the form of the thread cut on the pipe.

2. A machine as claimed in claim 1; in which the clamp arranged closer to the partof the pipe threads are cut.

3. A machine as claimed in claim 1 in which the clamp closer' to the part oi the pipe to be threaded is adapted to grip the pipe immediately 10 adjacent the part thereof to be threaded without interference with the thread-cutting tool.

WILLIAM'L. BEDiNINGHOFF. 

